ΣΤΡΟΓΓΥΛΗ ΤΡΑΠΕΖΑ 2: Καρδιαγγειακή υγεία και μακροζωία ΙI Γήρανση ηλεκτρικού συστήματος και καρδιακή βηματοδότηση: Η εμπειρία από τους βηματοδότες νεότερης γενιάς Πολυχρόνης Δηλαβέρης, MD, PhD, FESC Nucleus Member, e-cardiology WG at the ESC Διευθυντής Ε.Σ.Υ. A Πανεπιστημιακή Καρδιολογική Κλινική, Ιπποκράτειο Νοσοκομείο, Αθήνα
Myocardial fibrosis & electrical conductivity Aging is associated with the down-regulation and lateralization of connexins, the gap junctional proteins, in atrial myocytes, particularly in patients vulnerable to AF. Therefore, myocardial conductivity values in the fibrotic regions are reduced by 20% in the longitudinal direction and 50% in the transverse direction, compared to those in the remainder of atrial tissue. Luo MH, et al. Cardiology 2007;107:248. Kostin S, et al. Cardiovasc Res 2002; 54:361.
Yue L & Nattel S. Cardiovasc Res 2011 Myocardial fibrosis & electrical conductivity Increased myofibroblast infiltration further affects conductivity. Myofibroblasts are electrically coupled to adjacent myocytes, and are modeled as isotropic with reduced conductivity, representing the reduction of single gap junction conductance measured in myofibroblast myocyte pairs as compared to inter-myocyte junctions. Rook MB, et al. Am J Physiol 1992;263:C959.
Clinical mapping studies have observed areas of electrical silence, low voltage, fractionated electrograms, and altered and circuitous conduction associated with a predisposition for AF in heart failure, sinus node disease, aging, atrial septal defects, rheumatic heart disease, sleep apnea, and hypertension. Sanders P, et al. Circulation 2003;108:1461 1468. Sanders P, et al. Circulation 2004;109:1514 1522. Roberts-Thomson KC, et al. Heart Rhythm 2009;6:1000 1006. Dimitri H, et al. Heart Rhythm 2012;9:321 327. Medi C, et al. J Cardiovasc Electrophysiol 2011;22: 1317 1324. Decrease in transverse conduction velocity (enhanced anisotropy). Heterogeneity of conduction.. de Jong S, J Cardiovasc Pharmacol 2011
Atrial Fibrosis and Sinus Node Dysfunction Atrial arrhythmia-induced electrical remodeling is accompanied by structural remodeling that affects the sinus node. Autopsy studies have demonstrated degenerative fibrosis involving nodal and nodal atrial continuity in patients with SND. Demoulin JC & Kulbertus HE. Br Heart J 1978 In patients with AF presenting for catheter ablation, LGE-MRI quantification of atrial fibrosis demonstrates preferential LA involvement. Significant atrial fibrosis is associated with clinically significant SND requiring pacemaker implantation. Akoum N, et al. J Cardiovasc Electrophysiol 2012;23:44-50.
SSS SINUS ARREST AVB
Fig. 1. Maximum P-wave duration and P-wave dispersion in patients with idiopathic paroxysmal atrial fibrillation and in healthy control subjects. American Heart Journal, Volume 135, Issue 5, 1998, 733 738
Figure 1. Top left, top right, bottom right plots illustrate the association between P-wave duration and the risk of atrial fibrillation, death from cardiovascular causes, and stroke superimposed on a histogram of the population P-wave duration. Heart Rhythm, Volume 12, Issue 9, 2015, 1887 1895
Fig. 2. A. Typical ECG of advanced interatrial block (P-wave ± in leads II, III, and avf and duration 120 ms) in a patient with ischemic cardiomyopathy.
Small randomized trials suggested that patients with moderate-tosevere LV dysfunction might benefit from CRT instead of conventional RV apical pacing. Eur Heart J 2013 The primary endpoints of these trials were surrogate haemodynamic endpoints.
Heart Rhythm 2017;14:702 709
Heart Rhythm 2017;14:702 709
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Heart Rhythm 2012;9:728 735
ΣΥΜΠΕΡΑΣΜΑΤΑ Η προχωρημένη ηλικία με την συνεπαγόμενη επιβάρυνση στο ηλεκτρικό σύστημα της καρδιάς αυξάνει την ανάγκη για καρδιακή βηματοδότηση. Η γήρανση του πληθυσμού και η αυξημένη παρουσία χρόνιων καρδιακών παθήσεων αναμένεται να οδηγήσουν σε περαιτέρω αύξηση των αναγκών για βηματοδότηση της καρδιάς. Οι αλγόριθμοι στα σύγχρονα συστήματα καρδιακής βηματοδότησης, οι εναλλακτικές θέσεις και τρόποι βηματοδότησης και η καθιέρωση των βηματοδοτών χωρίς ηλεκτρόδια αποτελούν εξελίξεις που θα αποβούν ιδιαίτερα χρήσιμες στους ασθενείς προχωρημένης ηλικίας.
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